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Transformers are often used in electrical circuits to change the voltage of electricity flowing through a circuit.
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Voltage Transformers in Electric Circuits

Transformers (sometimes called "voltage transformers") are devices used in electrical circuits to change the voltage of electricity flowing in the circuit. Transformers can be used either to increase the voltage (called "stepping up") or decrease the voltage ("step down").

Transformers have two coils of wire in them. The coils of wire are wound around an iron core. The wires aren't connected to each other. One wire coil has more loops than the other. When AC (alternating current) electricity flows in one wire, it makes a magnetic field around that wire. The magnetic field causes electricity to flow in the other wire. Since the wire coils have different numbers of loops, the voltage in the second wire is different from the voltage in the first wire. That's how transformers change the voltage in a circuit.

Transformers are very efficient. Under normal conditions they transmit about 99% of the power that enters them (about 1% of the power is lost as heat).

When electricity travels from a power plant to your house, it passes through transformers along the way. High voltage is good to use for sending electricity long distances through wires because less energy is lost that way. However, we need low voltage electricity in our houses because it is safer. Transformers change the voltage of electricity as it moves from a power plant to your home.

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